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Message-Id: <20220201143425.19907-2-mathieu.desnoyers@efficios.com>
Date: Tue, 1 Feb 2022 09:34:25 -0500
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
"Paul E . McKenney" <paulmck@...nel.org>,
Boqun Feng <boqun.feng@...il.com>,
"H . Peter Anvin" <hpa@...or.com>, Paul Turner <pjt@...gle.com>,
linux-api@...r.kernel.org,
Christian Brauner <christian.brauner@...ntu.com>,
Florian Weimer <fw@...eb.enyo.de>, David.Laight@...LAB.COM,
carlos@...hat.com, Peter Oskolkov <posk@...k.io>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: [RFC PATCH v2 2/2] selftests/rseq: Implement rseq numa node id field selftest
Test the NUMA node id extension rseq field. Compare it against the value
returned by the getcpu(2) system call while pinned on a specific core.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
---
tools/testing/selftests/rseq/basic_test.c | 5 ++++
tools/testing/selftests/rseq/rseq-abi.h | 23 ++++++++++++++++
tools/testing/selftests/rseq/rseq.c | 24 ++++++++++++++---
tools/testing/selftests/rseq/rseq.h | 32 +++++++++++++++++++++++
4 files changed, 81 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/rseq/basic_test.c b/tools/testing/selftests/rseq/basic_test.c
index d8efbfb89193..a49b88cb20a3 100644
--- a/tools/testing/selftests/rseq/basic_test.c
+++ b/tools/testing/selftests/rseq/basic_test.c
@@ -22,6 +22,8 @@ void test_cpu_pointer(void)
CPU_ZERO(&test_affinity);
for (i = 0; i < CPU_SETSIZE; i++) {
if (CPU_ISSET(i, &affinity)) {
+ int node;
+
CPU_SET(i, &test_affinity);
sched_setaffinity(0, sizeof(test_affinity),
&test_affinity);
@@ -29,6 +31,9 @@ void test_cpu_pointer(void)
assert(rseq_current_cpu() == i);
assert(rseq_current_cpu_raw() == i);
assert(rseq_cpu_start() == i);
+ node = rseq_fallback_current_node();
+ assert(rseq_current_node() == node);
+ assert(rseq_current_node_raw() == node);
CPU_CLR(i, &test_affinity);
}
}
diff --git a/tools/testing/selftests/rseq/rseq-abi.h b/tools/testing/selftests/rseq/rseq-abi.h
index a8c44d9af71f..850827e8d089 100644
--- a/tools/testing/selftests/rseq/rseq-abi.h
+++ b/tools/testing/selftests/rseq/rseq-abi.h
@@ -146,6 +146,29 @@ struct rseq_abi {
* this thread.
*/
__u32 flags;
+ __u32 padding1[3];
+
+ /*
+ * This is the end of the original rseq ABI.
+ * This is a valid end of rseq ABI for the purpose of rseq registration
+ * rseq_len.
+ * The original rseq ABI use "sizeof(struct rseq)" on registration,
+ * thus requiring the padding above.
+ */
+
+ /*
+ * Restartable sequences node_id field. Updated by the kernel. Read by
+ * user-space with single-copy atomicity semantics. This field should
+ * only be read by the thread which registered this data structure.
+ * Aligned on 32-bit. Contains the current NUMA node ID.
+ */
+ __u32 node_id;
+
+ /*
+ * This is a valid end of rseq ABI for the purpose of rseq registration
+ * rseq_len. Use the offset immediately after the node_id field as
+ * rseq_len.
+ */
} __attribute__((aligned(4 * sizeof(__u64))));
#endif /* _RSEQ_ABI_H */
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 07ba0d463a96..4b0e68051db8 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -58,6 +58,11 @@ static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len,
return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
}
+static int sys_getcpu(unsigned *cpu, unsigned *node)
+{
+ return syscall(__NR_getcpu, cpu, node, NULL);
+}
+
int rseq_available(void)
{
int rc;
@@ -83,7 +88,7 @@ int rseq_register_current_thread(void)
/* Treat libc's ownership as a successful registration. */
return 0;
}
- rc = sys_rseq(&__rseq_abi, sizeof(struct rseq_abi), 0, RSEQ_SIG);
+ rc = sys_rseq(&__rseq_abi, rseq_offsetofend(struct rseq_abi, node_id), 0, RSEQ_SIG);
if (rc)
return -1;
assert(rseq_current_cpu_raw() >= 0);
@@ -98,7 +103,7 @@ int rseq_unregister_current_thread(void)
/* Treat libc's ownership as a successful unregistration. */
return 0;
}
- rc = sys_rseq(&__rseq_abi, sizeof(struct rseq_abi), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
+ rc = sys_rseq(&__rseq_abi, rseq_offsetofend(struct rseq_abi, node_id), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
if (rc)
return -1;
return 0;
@@ -121,7 +126,7 @@ void rseq_init(void)
return;
rseq_ownership = 1;
rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer();
- rseq_size = sizeof(struct rseq_abi);
+ rseq_size = rseq_offsetofend(struct rseq_abi, node_id);
rseq_flags = 0;
}
@@ -146,3 +151,16 @@ int32_t rseq_fallback_current_cpu(void)
}
return cpu;
}
+
+int32_t rseq_fallback_current_node(void)
+{
+ uint32_t cpu_id, node_id;
+ int ret;
+
+ ret = sys_getcpu(&cpu_id, &node_id);
+ if (ret) {
+ perror("sys_getcpu()");
+ return ret;
+ }
+ return (int32_t) node_id;
+}
diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h
index 6bd0ac466b4a..9d5ec4d66d98 100644
--- a/tools/testing/selftests/rseq/rseq.h
+++ b/tools/testing/selftests/rseq/rseq.h
@@ -16,9 +16,19 @@
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
+#include <stddef.h>
#include "rseq-abi.h"
#include "compiler.h"
+#ifndef rseq_sizeof_field
+#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+#endif
+
+#ifndef rseq_offsetofend
+#define rseq_offsetofend(TYPE, MEMBER) \
+ (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER))
+#endif
+
/*
* Empty code injection macros, override when testing.
* It is important to consider that the ASM injection macros need to be
@@ -115,6 +125,11 @@ int rseq_unregister_current_thread(void);
*/
int32_t rseq_fallback_current_cpu(void);
+/*
+ * Restartable sequence fallback for reading the current node number.
+ */
+int32_t rseq_fallback_current_node(void);
+
/*
* Values returned can be either the current CPU number, -1 (rseq is
* uninitialized), or -2 (rseq initialization has failed).
@@ -124,6 +139,15 @@ static inline int32_t rseq_current_cpu_raw(void)
return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id);
}
+/*
+ * Current NUMA node number.
+ */
+static inline uint32_t rseq_current_node_raw(void)
+{
+ assert((int) rseq_size >= rseq_offsetofend(struct rseq_abi, node_id));
+ return RSEQ_ACCESS_ONCE(rseq_get_abi()->node_id);
+}
+
/*
* Returns a possible CPU number, which is typically the current CPU.
* The returned CPU number can be used to prepare for an rseq critical
@@ -150,6 +174,14 @@ static inline uint32_t rseq_current_cpu(void)
return cpu;
}
+static inline uint32_t rseq_current_node(void)
+{
+ if (rseq_likely((int) rseq_size >= rseq_offsetofend(struct rseq_abi, node_id)))
+ return rseq_current_node_raw();
+ else
+ return rseq_fallback_current_node();
+}
+
static inline void rseq_clear_rseq_cs(void)
{
RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0);
--
2.17.1
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